It is considered that the main specific feature of organisms with negligible senescence is that the probability of adult individuals dying does not change with their age. However, there are almost no direct observations that could either confirm or refute this statement; moreover, such data are unobtainable for many species. From this standpoint, we have studied the freshwater pearl mussel, a species displaying signs of negligible senescence (continuous growth, long maximal lifespan, and the ability to reproduce during its entire life). Examination of individuals that have died in a natural environment suggests that the probability of their death increases with age, i.e., this species is subject to aging. This fact, as well as the gaps in substantiation of the concept of "negligible senescence", shows that the concept in question is erroneous.